Colitis: Symptoms, Types, Causes and Treatment

Colitis, or inflammation of the colon, is a condition that can dramatically impact quality of life. With a rising global incidence, understanding colitis is more important than ever. Whether you are a patient, caregiver, or health professional, this guide brings together the latest scientific insights on colitis—its symptoms, classifications, causes, and treatments—drawing from high-quality research sources. Let’s dive in and shed light on this multifaceted condition.

Symptoms of Colitis

Colitis often announces itself with a range of gastrointestinal and sometimes systemic symptoms. Recognizing these early signs can lead to quicker diagnosis and improved management. While the specific symptoms can vary depending on the type and severity of colitis, certain patterns recur frequently.

Symptom	Description	Typical in...	Source(s)
Bloody diarrhea	Blood mixed with loose stools	Ulcerative colitis	2 3 4 5 6 7 8
Abdominal pain	Cramping or discomfort	All types	2 3 4 5 6 8
Fecal urgency	Sudden, strong need to defecate	Ulcerative colitis	1 2 3 4 5
Tenesmus	Feeling of incomplete evacuation	Ulcerative colitis	1 2 3 5
Mucus in stool	Passage of mucus with stool	Ulcerative colitis	4 5
Constipation	Hard stools, difficult passage	Some UC patients	1 5
Fatigue/weakness	Tiredness, reduced energy	More in Crohn’s, also UC	4 5
Weight loss	Unintentional weight reduction	More in Crohn’s, also UC	5

Table 1: Key Symptoms

Understanding the Symptom Spectrum

Colitis symptoms can be both distressing and disruptive. Here’s a closer look at what patients may experience:

Gastrointestinal Symptoms

• Bloody Diarrhea: This is the hallmark of ulcerative colitis (UC), reported by over 85% of newly diagnosed patients. Diarrhea is often accompanied by visible blood, which helps distinguish UC from other types of colitis and Crohn’s disease 2 3 4 5 6 7 8.
• Fecal Urgency and Tenesmus: Many patients feel a sudden, intense need to use the bathroom and may experience tenesmus—a sensation of incomplete evacuation. These symptoms reflect irritation or inflammation in the distal colon and rectum and are highly prevalent in active UC (more than 80% in some studies) 1 2 3 4 5.
• Abdominal Pain and Cramping: While not as specific, abdominal discomfort is common in both UC and Crohn’s disease, though classical UC tends to be less painful than Crohn’s 2 3 4 5 6.
• Constipation: Surprisingly, a subset of UC patients can suffer from constipation, especially proximal constipation combined with distal irritability—a paradoxical feature of active disease 1 5.

Other Bowel-Related Manifestations

• Mucus in Stool: This is seen more commonly in UC and signals mucosal inflammation 4 5.
• Incontinence: With severe urgency, fecal incontinence can occur, particularly when inflammation is significant 5.
• Passage of Blood from Anus: In addition to blood mixed in stool, some patients notice blood independently during defecation 4.

Systemic and Extraintestinal Symptoms

• Fatigue and Weakness: Common in both UC and Crohn’s, though more pronounced in Crohn’s. Chronic inflammation, anemia, and poor nutrient absorption contribute to this symptom 4 5.
• Weight Loss: More common in Crohn’s but can occur in severe or untreated UC 5.

Symptom Profiles

Distinct symptom “phenotypes” help differentiate UC from Crohn’s disease. For example:

• UC: Bloody diarrhea, urgency, mucus, tenesmus, constipation (distal involvement)
• Crohn’s: Abdominal pain, weight loss, systemic symptoms, less blood in stool 4 5

Types of Colitis

Colitis is not a one-size-fits-all diagnosis. There are several types, each with unique features. Understanding these distinctions is crucial for effective management.

Type	Key Features	Extent/Location	Source(s)
Ulcerative Colitis	Continuous inflammation, starts at rectum	Colon only	2 3 6 7 8
Crohn’s Disease	Patchy, transmural inflammation	Any GI tract, often ileum	4 5 8 10
Indeterminate	Features of both UC and Crohn’s	Colon	9
Infectious Colitis	Acute, bacteria/virus/protozoa cause	Any part of colon	13
Microscopic Colitis	Chronic diarrhea, normal endoscopy, histology	Colon mucosa	–
Ischemic Colitis	Sudden, due to loss of blood flow	Usually splenic flexure	–
Allergic Colitis	Immune reaction, often food-related	Infants and young children	14

Table 2: Types of Colitis

The Major Types Explained

Ulcerative Colitis (UC)

• Defining Features: Chronic, idiopathic inflammation confined to the colon and rectum. Inflammation is continuous (not patchy) and limited to the mucosal layer 2 3 6 7 8.
• Subtypes by Extent:
  • Proctitis: Only rectum
  • Left-sided Colitis: Up to splenic flexure
  • Pancolitis: Entire colon 8
• Symptoms: Bloody diarrhea, urgency, tenesmus, mucus in stool 2 3 4 5 6 7 8
• Complications: Colorectal cancer, extraintestinal manifestations (arthritis, primary sclerosing cholangitis) 8

Crohn’s Disease

• Defining Features: May affect any segment of the gastrointestinal tract (mouth to anus), but most commonly involves the terminal ileum and/or colon. Inflammation is patchy (“skip lesions”), transmural (affecting entire bowel wall), and often causes fistulae or strictures 4 5 8 10.
• Symptoms: Abdominal pain, weight loss, diarrhea (less blood than UC), fatigue 4 5
• Systemic Features: More extraintestinal symptoms than UC 5

Indeterminate Colitis

• When It’s Used: Sometimes, colonic inflammation has overlapping features of UC and Crohn’s, making definitive classification difficult. The term “indeterminate colitis” is used in about 10–15% of cases, particularly after surgical specimen review 9.

Infectious Colitis

• Acute Onset: Caused by bacteria (Salmonella, Shigella, Campylobacter), viruses, or parasites. Typically self-limited, but can mimic IBD 13.

Microscopic Colitis

• Diagnosis by Biopsy: Chronic watery diarrhea with normal colonoscopy, diagnosed histologically as either collagenous or lymphocytic colitis. Not covered in detail in the sources, but important to note.

Ischemic Colitis

• Vascular Cause: Due to compromised blood flow, often in older adults or those with vascular disease. Presents with sudden pain and bloody diarrhea.

Allergic (Eosinophilic) Colitis

• Pediatric Focus: Most common cause in infants is food allergy, often to cow’s milk or soy protein. Symptoms resolve with dietary exclusion 14.

Causes of Colitis

Pinpointing the cause of colitis is essential for effective treatment. While some forms have clear triggers, others—like UC and Crohn’s—remain idiopathic, with a combination of genetic, immune, microbial, and environmental factors at play.

Cause	Description	Strongly Linked to	Source(s)
Immune Dysregulation	Abnormal immune response to gut contents	Ulcerative colitis, Crohn’s	6 8 10
Genetic Susceptibility	Family/genetic risk factors	UC, Crohn’s	6 10
Microbiota Imbalance	Disrupted gut bacteria (“dysbiosis”)	UC, Crohn’s	10 11 13
Infection	Bacteria, viruses (CMV in IBD patients)	Infectious/CMV colitis	12 13
Food Allergy	Immune reaction to dietary proteins	Allergic colitis (infants)	14
Vascular Insufficiency	Reduced blood flow to colon	Ischemic colitis	–
Environmental Factors	Smoking, NSAIDs, stress, diet	All types	6 10

Table 3: Causes of Colitis

Dissecting the Causes

Immune and Genetic Factors

• Immune Dysregulation: Both UC and Crohn’s disease are considered immune-mediated. The immune system reacts abnormally to harmless gut bacteria or dietary antigens, leading to chronic inflammation 6 8 10.
• Genetic Risk: Family history increases susceptibility. Over 200 genetic loci have been implicated, each contributing to immune regulation, barrier function, or microbial sensing 6 10.

Microbiome and Environmental Triggers

• Gut Microbiota: A “dysbiosis” or imbalance in the gut’s microbial community is a key driver. Certain bacteria (e.g., Klebsiella, Proteus) can trigger or perpetuate inflammation, especially in genetically susceptible hosts 10 11 13.
• Environmental Triggers: Infections, antibiotics, NSAIDs, stress, and smoking can disrupt the mucosal barrier or microbiome, triggering disease onset or flares 6 10.

Infectious and Allergic Causes

• Infections: Acute colitis often results from enteric pathogens. In immunosuppressed IBD patients, CMV can cause or worsen colitis and requires special testing and treatment 12 13.
• Food Allergies: In infants, allergic colitis is almost always due to immune responses to cow’s milk, soy, or other proteins. Elimination diets are curative 14.

Ischemia and Other Rare Causes

• Ischemic Colitis: Not immune-mediated, this type occurs when blood flow to the colon is interrupted, often due to cardiovascular disease, medications, or surgery.

Treatment of Colitis

The treatment of colitis is as diverse as its causes. Management strategies depend on the underlying type, severity, and complications. Let’s explore the current landscape of evidence-based therapies.

Approach	Description	Used for	Source(s)
5-Aminosalicylates	Anti-inflammatory drugs (e.g., mesalamine)	Mild to moderate UC	2 3 6 7
Corticosteroids	Systemic or topical steroids	Moderate to severe UC, flares	2 3 6 7
Immunosuppressants	Azathioprine, 6-MP, cyclosporine	Steroid-sparing, severe cases	2 3 6
Biologic Therapies	Anti-TNF, anti-integrin, JAK inhibitors	Moderate to severe, refractory	2 3 6 7
Antibiotics	For infectious or secondary bacterial infection	Infectious colitis, Crohn’s	13
Dietary Modification	Elimination diets for allergies, supportive care	Allergic colitis, IBD adjunct	14
Probiotics/Synbiotics	Modulate gut flora, reduce inflammation	Adjunct in UC, experimental	17 18 19
Surgery	Colectomy, proctocolectomy	Refractory UC, cancer, ischemia	2 3 6
Natural/Herbal Agents	Plant-based anti-inflammatories	Adjunct in UC, under study	15 16
Preventive Care	Vaccinations, cancer screening, bone health	All chronic IBD	2 3

Table 4: Treatment Options

Approaches to Colitis Treatment

Pharmacological Therapies

• 5-Aminosalicylates (5-ASA): The cornerstone for mild-to-moderate UC, these drugs (mesalamine, sulfasalazine) reduce mucosal inflammation and are available in oral or rectal formulations 2 3 6 7.
• Corticosteroids: Used for moderate to severe flares or when 5-ASA fails. While effective for remission induction, they are not suitable for long-term use due to side effects 2 3 6 7.
• Immunosuppressants: Agents such as azathioprine or 6-mercaptopurine help maintain remission and are used as steroid-sparing drugs 2 3 6.
• Biologics: Anti-TNF agents (infliximab, adalimumab), anti-integrins, and JAK inhibitors target specific immune pathways and are reserved for moderate to severe or refractory cases 2 3 6 7.

Microbiome-Targeted Interventions

• Probiotics and Synbiotics: Multi-strain probiotics and synbiotic supplements (prebiotics + probiotics) show promise in restoring microbial balance, enhancing barrier function, and reducing inflammation in experimental models and early studies 17 18 19.
• Engineered Probiotics: Novel approaches, like live engineered E. coli producing beneficial metabolites (e.g., 3-hydroxybutyrate), are being tested in experimental colitis with encouraging results 19.

Dietary and Natural Therapies

• Elimination Diets: Essential for allergic colitis in infants; removing cow’s milk or other allergenic foods leads to resolution 14.
• Herbal/Natural Agents: Compounds such as curcumin, boswellic acid, and others are under investigation for their anti-inflammatory properties and lower side-effect profiles 15 16. However, more research is needed before widespread adoption.

Surgical and Supportive Care

• Surgery: Approximately 15% of UC patients may eventually require colectomy or proctocolectomy due to refractory disease or cancer risk 2 3 6.
• Preventive Health: Management includes cancer surveillance, vaccination, bone health monitoring, and screening for extraintestinal manifestations (arthritis, liver disease, depression) 2 3.

Special Considerations

• CMV Colitis: In IBD patients, especially those on immunosuppressives, CMV infection must be ruled out in severe flares. Treatment may require antiviral drugs 12.
• Allergic Colitis: In infants, food exclusion is usually curative 14.
• Infectious Colitis: Requires targeted antimicrobial therapy based on the causative organism 13.

Conclusion

Colitis is a complex group of disorders characterized by inflammation of the colon, with a wide spectrum of symptoms, causes, and treatments. Early recognition and precise diagnosis are key to effective care. Here are the main takeaways:

• Symptoms are diverse: From bloody diarrhea and urgency to fatigue and weight loss, symptoms depend on the type and severity of colitis.
• Multiple types exist: Ulcerative colitis and Crohn’s are the most common chronic forms, but indeterminate, infectious, ischemic, and allergic colitis are also important.
• Causes are multifactorial: Genetics, immune system dysregulation, microbiome changes, infections, and in some cases, food allergies or vascular issues are implicated.
• Treatments are expanding: Options range from traditional drugs (5-ASA, steroids, immunosuppressants) to biologics, dietary changes, probiotics, and surgery. Preventive care and new therapies continue to evolve.

By understanding the nuances of colitis, patients and clinicians can work together to tailor therapy, improve outcomes, and enhance quality of life.